Science Do as instructed

We should keep them in refrigerator because in refrigerator, due to low temperature, fruits and vegetables do not spoil and biological and chemical reactions in fruits and vegetables are slowed down at low temperature.

We should tell him to wear gloves before serving panipuri because dirty hands contain dirt and germs which are harmful to us.

We should tell them to sell the covered sweets because uncovered sweets are harmful to eat because it contains dust, dirt and germs. And buyers also should not purchase these uncovered sweets.

Sometimes due to sudden rain, wheat gets a bit moist. Possible remedies: Do not store the moist wheat, it gets spoiled due to fungus so first sundry it and then store in a clean and dry container to avoid microbial growth.

Sometimes in a hurry if we cook the rice it is underdone.
Possible remedies: Use proper pressure cooker to cook the rice.